Add a new GetNegotiatedProtocol method to StreamSocket and implement in all subclasses.

net/socket/tcp_client_socket_libevent.h

Index: net/socket/tcp_client_socket_libevent.h
diff --git a/net/socket/tcp_client_socket_libevent.h b/net/socket/tcp_client_socket_libevent.h
index a6aa24188f2261780a4859287de5c83e2eecf7a8..5519f3cbf5504bb05adcdc375796c9c91a5413f9 100644
--- a/net/socket/tcp_client_socket_libevent.h
+++ b/net/socket/tcp_client_socket_libevent.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -56,6 +56,7 @@ class NET_EXPORT_PRIVATE TCPClientSocketLibevent : public StreamSocket,
   virtual bool UsingTCPFastOpen() const OVERRIDE;
   virtual int64 NumBytesRead() const OVERRIDE;
   virtual base::TimeDelta GetConnectTimeMicros() const OVERRIDE;
+  virtual NextProto GetNegotiatedProtocol() const OVERRIDE;
 
   // Socket implementation.
   // Multiple outstanding requests are not supported.